COLOGNE, Germany - Pope Benedict XVI warned today of rising anti-Semitism and hostility to foreigners, winning a standing ovation from members of Germany's oldest Jewish community during a visit to a rebuilt synagogue that had been destroyed by the Nazis.

With the shrill sound of a ram's horn and a choir chanting in Hebrew "peace be with you," Benedict became only the second pope to visit a synagogue, praying and remembering Holocaust victims.

"Today, sadly, we are witnessing the rise of new signs of anti-Semitism and various forms of a general hostility toward foreigners," he said.

Benedict said progress had been made, but "much more remains to be done. We must come to know one another much more and much better."

He did not elaborate on his warning except to call for more vigilance, receiving loud applause from the audience after his remarks.

Earlier, Benedict stood quietly with his hands clasped during a Hebrew prayer before a memorial to the 6 million Jews killed by Nazi Germany, and strode into the main hall as the choir sang, "Shalom alechem," or "peace be with you."

A shofar, or ram's horn, sounded as the pope sat down at the front. He then listened intently to the cantor's singing in the blue-domed Roonstrasse Synagogue, which was destroyed during the infamous Kristallnacht pogrom in 1938.

Rabbi Netanel Teitlebaum called his visit "a step toward peace between all peoples."

The pope underlined his commitment to continue in the path of his predecessor, John Paul II, who made the first papal visit to a synagogue in Rome in 1986 and improved relations between Catholics and Jews.

"Today I, too, wish to reaffirm that I intend to continue on the path toward improved relations and friendship with the Jewish people, following the decisive lead given by John Paul II," said Benedict, who did much of the theological groundwork for John Paul's outreach while serving as a Vatican official in charge of doctrine.

Outreach to Jews and Muslims is one of the themes of Benedict's first foreign trip since his election as pope on April 19 in conjunction with the World Youth Day festival that has drawn over 300,000 young people to Cologne.

Progress had been made, he said, but "much more remains to be done. We must come to know one another much more and much better."

He did not say where or among whom he saw rising signs of anti-Semitism, but called simply for more vigilance and stressed the Roman Catholic Church's belief in the equality of all and respect for human life. He was answered with loud applause from the audience.

The German-born pope did not discuss his own personal experience of World War II - being unwillingly enrolled in the Hitler Youth as a teenager and risking execution by deserting the German army at the end of the war.

He was given a shofar as a gift from the congregation, which has roots going back to Roman times. Some 11,000 Jews from Cologne died in the Holocaust; the community has rebounded in the past decade with the influx of Jews from the former Soviet Union and now numbers 5,000.

Benedict's visit appeared to have helped smooth over a dispute between the Vatican and Israel that arose after the Israeli government faulted Benedict for not mentioning attacks on Israelis in a recent condemnation of terrorism. The Vatican responded with a terse statement asking the Israelis not to tell the pope what to say.